Watching this year’s Grammy Awards, it’s clear hip-hop is the dominant genre in popular music. But back in the 1980s, it was an influential but still underground style looking for a place on the charts—and some mainstream respect. That is, until Run-D.M.C. met Aerosmith. This month, how some out-of-favor ’70s rockers teamed up with the top crew in rap to remake an old hit—in the process, opening lanes for a trio of punks-turned-emcees and a witty hip-hop Lothario. We’re still feeling the reverberations today.